Buying a car can cost you in the thousands range. Maintaining the vehicle such as, oil change, spark plugs, filters, etc can be like in the 100's range per year. Add fuel costs too.
Then add the costs of having problems with your car. A freaking alternator can cost like $40- $60. A tire in the other hand costs betwee $70-$200 and that is just one freaking tire. Buy 4 tires if they all have worn treads and you are paying $200-400+ bucks
These numbers are like if you can fix the car yourself without paying the technicians. If you take your vehicle for repair, then it's going to cost more.
Then add what if your car doesn't start on the highway. Your going to face a $200-$300 towing fee plus extra to fix the car.
Now taking a Public transportation, you don't need to worry about fuel running out, changing tires, worrying about the alternator going bad, or getting the vehicle robbed.
On one hand, you would buy a car and face with all the costs of maintenance and fuel costs? or on the other hand, would you just take a train or bus and sit relax and read Slashdot on your notebook?